Technical area The present invention relates to a valve intended to control the pressure in a pipe in which a gas is conducted, for example in the form of a release valve for controlling an overpressure of a turbo charged engine of a vehicle.

Background The most modern turbo charged petrol engines are equipped with a so called release valve, that releases the overpressure that is generated by the turbo when driving at decreased speed. The sudden pressure increase that arises when driving at decreased speed, that is when the accelerator pedal is released, may otherwise damage the turbo aggregate, hoses, intercooler and other components in the engine, if a release valve not had been arranged to release this pressure increase.

The overpressure can reach the magnitude of five times the usual charge pressure at these temporary pressure increases.

If the usual charge pressure is increased, that is"trimmed", problems may arise since the originally installed release valve, intended for the originally charge pressure, is not designed for the new increased charge pressure. Then the originally installed release valve has to be replaced by a new release valve, designed for the new charge pressure and the new capacity. Conventional release valves are usually welded on the existing pressure pipe from the turbo, which means that the original release valve then has to be cut of and a new release valve installed at replacement of release valve.

The conventional release valves (se also fig. 1, and also more close description hereinafter with reference to the drawings), comprises a hollow valve housing that in one end is assembled, alternatively firmly welded or glued, against a

pressure pipe that has an opening that communicates with the open hollow compartment of the valve housing. In the valve housing there is arranged a movable, spring-loaded valve body, that at usual charge pressure is spring-loaded to rest and seal against a seat of valve in vicinity of the end of the valve housing that is firmly welded against the pressure pipe.

At a larger difference between the pressure before and after the throttle valve, the movable valve body is influenced to move, whereby openings in the side walls of the valve housing is uncovered, through which the air flow with the overpressure from the pressure pipe can be released. Nevertheless, this conventional construction means that there exists a space between the opening of the pressure pipe and the seat of the valve through which the air flow have to pass before it is released through the openings of the walls of the valve housing. Also air may flow into this compartment, also when the valve body rests and seals against the seat of the valve.

Accordingly, the pressure pipe has a larger cross-sectional area at the position of the release valve than what the pressure pipe has got before and after the release valve. This compartment results in a turbulent air flow through the pressure pipe when the release valve is closed. Moreover, this conventional release valve results in that the air flow has a relatively long way out when the flow also is redirected in the valve itself before it is released. Above all, this conventional release valve results in that the opening area of the valve becomes relatively limited. The passage that the released air is passing through in the release valve becomes relatively small, which results in that the turbo is slowed down from further spinning, that is the number of revolutions in the turbo aggregate is not maintained in sufficient extent, such that it can be utilised at the next turbo charge or when stepping on the gas.

Description of the invention One object with the present invention is to achieve a valve, intended to control the pressure in a pipe in which a gas is conveyed, that at least partially eliminates those drawbacks that are associated with apparatuses according to the state of the art. Yet one object is to provide a valve that can be easily installed and removed on existing pressure pipes, and also that can be produced cost-efficiently. It is further an object to achieve a release valve, intended for control of an overpressure of a turbo charged engine of a vehicle, that can maintain a higher number of revolutions at the turbo aggregate, compared to conventional release valves, at decreased gas and which maintained rotation speed can be utilized at the next turbo charge or the next increased gas.

This object is achieved by a valve intended to control the pressure in a pipe in which a gas is conveyed, for example in the shape of a release valve for controlling of an overpressure at a turbo charged engine of a vehicle, according to the present invention as defined in claim 1. The valve comprises a movable valve body arranged in a valve housing that has through apertures in the wall sections of the valve housing. The valve housing comprises a spring arranged in a chamber in which the valve body is movable. The valve further comprises a control pressure conduit for feeding of a partial flow of said gas that is connected to said chamber. The. spring is arranged to spring-load the valve body at a primary pressure of the gas such that the valve body is displaced in a sealed position over the apertures in the wall sections. A secondary pressure of the partial flow of gas in the control pressure conduit, lower than said primary pressure, that provides a low pressure ratio between the surrounding atmospheric pressure outside the pipe and said secondary pressure, reduces the spring-loading on the valve body such

that the valve body is moved in the chamber and at least partially uncovers the apertures in the wall sections whereby gas in the pipe can be exhausted through the apertures. The wall sections of the valve housing forms an extended part of the pipe in which the gas is conveyed.

One advantage with this solution according to the present invention is that the openings in the wall section of the valve communicates directly with the surrounding atmosphere, alternately a conduit for recirculation of exhausted gas from the valve, in that the wall sections of the valve housing constitutes a direct extended part of the pipe itself, as for example is a pressure pipe or a charge air pipe or an intake manifold of a vehicle engine, in which gas is conveyed under pressure, such as e. g. air. Yet an advantage according to the present invention is that a considerable more laminar flow of the air is achieved at the valve, since the present valve eliminates the projecting compartment from the pressure pipe that is unavoidable for mounted conventional release valves on pressure pipes. These makes it possible that a valve, according to the present invention, to a great extent can maintain a higher rotational speed than what is possible with conventional release valves and faster build up a new charge pressure. The valve according to the present invention also result in that the gas that is to be removed through the-valve has an easy way out compared to conventional release valves where the air shall be angled two times before it reaches out.

Above all, the present valve makes a larger aperture area possible compared to conventional release valves, which results in low heat release in the valve itself and besides in the tube system and also less requirement of cooling of the valve. Conventional release valves closes and opens immediately soon after adjusted maximal charge pressure. The valve according to the present invention has a design that

allows opening and closing when the charge pressure corresponds to atmospheric pressure.

The valve according to the present invention is not limited to the preferred field of application such as release valve for controlling of an overpressure at a turbo charged engine of a vehicle, but can be used in different kind of pneumatic applications and in general serve to control overpressure in pipes for conveyance of gas. Gas mentioned in accordance with the present invention preferably constitutes of air.

Additional advantages and features according to embodiments of the invention is evident from the claims, and also in the following from the description of the embodiments.

Description of drawings The present invention will now be described in more detail in embodiments, with reference to accompanying drawings, without limiting the interpretation of the invention thereto, where fig. 1 schematically shows, in a cross sectional view, a conventional release valve arranged to a charged air pipe according to the state of the art, fig. 2A schematically shows a cross sectional longitudinal view of a valve. according to the present invention in a closed position, fig. 2B schematically shows in a cross sectional longitudinal view the valve in fig. 2A in an opened position, fig. 2C schematically shows a side view of the valve in fig. 2A-B in an opened position, and fig. 3 schematically shows in a cross sectional view of the valve according to figs. 2A-C arranged in pressure pipe between the compressor and a throttle valve in an engine of a vehicle.

Detailed description of embodiments Fig. 1 shows a conventional release valve 2 that comprises a hollow valve housing 4 that in one end is firmly welded against a charge air pipe 6, i. e. a pressure pipe, which is the pipe that conveys air with a specific charge pressure from a turbo aggregate to the engine (not shown). The purpose of the release valve is to dispose of a remaining turbo pressure that is generated of the turbo at decreased driving speed. The air charging pipe 6 has an opening 8 that communicates with the open hollow compartment 10 of the valve housing. In the valve housing 4 is arranged a movable, spring- loaded valve body 12, that at normal charge pressure is spring-loaded to rest and seal against a seat of valve 14 in the vicinity of the firmly welded end of the valve housing against the pipe 6. A coil spring 16 is arranged in a compartment 18 that is formed of the valve body and the outer end of the valve housing 4. The release valve is controlled of by demand of the engine with respect to the pressure, that is controlled by the accelerator pedal, in the inlet pipes in connection to the engine. A control pressure conduit 20 is for this purpose arranged to the inlet pipes and to the chamber 18 of the valve body. A partial flow of the air with the existing pressure at the inlet pipes is thus brought in the control pressure conduit 20 into the chamber 18 of the release valve.

At an overpressure at the inlet pipes, the valve body 12 is thus pressed against the valve seat by means of the overpressure that is conveyed into the chamber via the control pressure conduit. A throttle valve (not shown) that is controlled by the actuation of the accelerator pedal is arranged in the pipe 6 in the direction of the flow S after the release valve. When the accelerator pedal is released, the throttle valve closes the conveyance of air to the engine and

the inlet pipes. A considerable overpressure is then formed in the part of the pipe 6 that is in connection between the compressor and the release valve. This overpressure brings a pressure from the pipe to the valve body 12. At the same time an underpressure is produced in the part of the pipe 6 that now is closed for air conveyance between the throttle valve and the engine. This underpressure of the air is conveyed via the control pressure pipe into the chamber 18 of the release valve whereby the pressure that press the valve body 12 against the valve seat 14 ceases. The pressure difference between the overpressure in the pipe and the underpressure in the chamber results in that the valve body 12 is pressed away from the valve seat 14 whereby apertures 22, that communicates with-ambient atmospheric pressure outside the pipe, is uncovered such that the overpressure in the pipe 6 can be decreased.

When stepping on the gas, the throttle valve is opened again whereby the pressure in the inlet pipes is raised, simultaneous as the partial flow of air with raised pressure that is led into the chamber 18 in the release valve press the valve body 12 back against the valve seat 14. When the valve body 12 again seals against the valve seat 14, the apertures 22 in the walls of the valve housing are closed.

However, this conventional construction means that there is a space having a depth h between the opening 8 of the pipe and the valve seat 14 through which the flow of air has to pass before it is disposed of through the apertures 22 in the walls of the valve housing. Also air may flow to this-space even when the valve body 12 rests and seals against the valve seat 14. Thus, at the position of the release valve the pipe has a larger cross sectional area than before and after the release valve. This space results in a turbulent flow of air through the pipe when the release valve is closed. This

conventional release valve further results in that the air flow has a relatively long way out when the flow also is redirected in the valve itself before it is let out. Above all, this conventional release valve brings about that the opening area that is formed by the apertures 22 of the valve becomes relatively limited. The passage in the release valve, that the released air shall get through, becomes relatively small, which makes the turbo to slow down quicker from further spinning, than what is the case with the valve according to the present invention, i. e. the number of revolutions in the compressor is not maintained in sufficient degree such that it can be utilised at the next turbo charge at increased gas. The spring 16 that loads the valve body to rest against the valve seat is relatively strong to counteract that the release valve "falsely opens", e. g. at little pressure difference between the pressure in the pipe 6 and the pressure in the chamber 18.

Hereafter in the following is described a valve in accordance with the present invention with reference to figs.

2A-C and 3, which shows a valve 30 intended to control the pressure in a pipe 32 (illustrated by broken lines in figs.

2A-B) in which gas is conveyed. In figs. 2A-C and 3 the valve 30 is shown in the shape of a release valve for'controlling an overpressure in a turbo charged engine of a vehicle. The valve comprises a movable valve body 34 arranged in a valve housing 35 that has through apertures 36 in the wall sections 38 of the valve housing. Suitably the through apertures 36 in the wall sections has a longitudinal extension L that is parallel to the longitudinal extension L of the wall sections 38. The apertures 36 in the wall sections are suitably evenly spread around the circumference of the valve housing. At the area of the apertures 36 in the wall sections of the valve, the open area that is made up of the through apertures 36 can be larger than the area that constitutes of wall surface 40 between the

apertures 36. The open area of the apertures can constitute a substantial part of the valve at this section and is only limited by the strength that a necessary remaining wall surface must have to support the shape of the valve.

The valve housing comprises a spring arranged in a chamber 42 in which the valve body 34 is movable. At an end section 44 of the valve housing, on the opposite side of the apertures in comparison with the section of the valve where the chamber 42 is arranged, a valve seat 46 is formed agiasnt which the movable valve body 34 rests and seals in the closed position when the valve body 34 closes the air access to the apertures 36. The valve seat can suitably comprise sealing means 48, such as an o-ring or a grounded valve seat, at the apertures that prevents leakage of gas through the apertures 36 when the valve body is displaced for sealing of the apertures.

In accordance with the present invention, the wall sections 38 of the valve housing forms an extended part of the pipe 32 in which the gas is conveyed. In that respect the installation of the valve is simplified compared to a conventional release valve (se fig. 1) that is welded or glued in position. At the installation of a valve according to the present invention, a part of the pressure pipe and the valve is instead arranged in the position of the cut off part of the pipe by e. g. hose clips, hoses and/or the similar.

The chamber 42 is formed in a space that is defined by the inner wall 50 and an outer wall 52 of the valve housing along a partial-section 54 of the valve. Thus, the chamber 42 forms an annular space that along a partial section 54 of the valve surrounds the tubular lead-through in the valve in which the gas is conveyed. To the chamber 42 is arranged a control pressure conduit 56 for supply of a partial flow of said gas that is connected to said chamber. In the annular chamber is a

spring 58 arranged, suitably a coil spring, which spring thus has a diameter that corresponds with the diameter of the annular chamber 42. The spring 58 is arranged to load the valve body 34 at a primary pressure of the gas such that the valve body is displaced in a sealed position over the apertures 36 in the wall sections. The primary pressure in operation, i. e. when the engine is in operation, is higher than ambient atmospheric pressure outside the valve and the pipe 32. Ambient atmospheric pressure is around normal air pressure, i. e. about 1 atmosphere. A secondary pressure of the partial flow of gas in the control pressure conduit 56, lower than said primary pressure, that provides a low pressure difference between the atmospheric pressure and said secondary pressure, reduces the spring-load on the valve body 34 such that the valve body is moved in the chamber 42 and at least partially uncovers the apertures 36 in the wall sections whereby gas in the pipe can be evacuated through the apertures.

The part of the valve body 34 that is arranged in the chamber is suitably provided with sealing means 60, which prevents leakage of gas in the chamber 42 supplied by the control pressure conduit 56. A partial flow of the air having the pressure that exists at the inlet pipes is thus led in the control pressure conduit into the chamber of the release valve. At an overpressure at the inlet pipes 62 (se fig. 3) the valve body is thus pressed against the valve seat 46 by means of the overpressure that is led into the chamber 42 via the control pressure conduit 56. A throttle valve 64 (se fig.

3), that is controlled by the actuation of the accelerator pedal, is arranged in the pipe 32 in the direction of the flow S after the release valve 30.

The wall section 38 of the valve housing forms an extended part of the pipe 32 in which the gas is conveyed

whereby preferably an inner opened cross-sectional area A formed of the wall sections of the valve housing according to a preferred embodiment is substantially as large as an inner opened cross-sectional area A2 of the pipe 32. However, as evident from the figs. 2A-B, a cross-sectional area A3 at the apertures 36 can be somewhat larger than in the valve as for the rest. As evident in fig. 2A-B, the inner wall in the direction of the flow S of the gas passes into a chamfered end 66, which height can be about 1 mm. This does not influence the laminar flow through the valve to any appreciable extent.

By the chamfered end 66 that forms a divergent tubing in the direction of the flow. in the valve, a pressure increase is achieved that may result in enhanced effect to the engine 68.

The operation of the valve according to the present invention is as follows: Thus, at an overpressure at the inlet pipes the valve body 34 is pressed-against the valve seat 46 by means of the overpressure that is conveyed into the chamber 42 via the control pressure conduit 56. A throttle valve 64, which is controlled by the actuation of the accelerator pedal, is arranged in the pipe 32 in the direction of the flow S after the release valve. When the accelerator pedal is released, the throttle valve 64 closes the conveyance of air to the engine 68 and the inlet pipes 62. A considerable overpressure is then formed in the pressure pipe 32 and in the valve 30 that thus is an extended part of the pressure pipe 32. Simultaneously is an underpressure created in the part 70 of the pressure pipe 32 that now is closed for conveyance of air between the throttle valve 64 and the engine 68. This underpressure of the air is led via control pressure conduit 56 into the chamber 42 of the release valve whereby the pressure that press the valve body 43 against the valve seat 46 ceases. The pressure difference between the atmospheric pressure at the outside 33

of the valve at the sealing part of the valve body 34 and the underpressure in the chamber results in that the valve body 34 is pressed, alternatively is sucked, away from the valve seat 46 whereby the apertures 36, that communicates with the ambient atmospheric pressure outside the pipe, is uncovered such that the overpressure in the pipe can be released without resistance, which results in a relatively small decrease in rotational speed of the turbo aggregate 72. According to an embodiment (not shown), a recirculation conduit can be arranged in direct connection to the apertures 36, which conduit brings back evacuated air from the valve to a suitable position in the system (se fig. 3), which is advantageous form an environmental point of view. Fig. 3 also shows the compressor 74 in connection to the pressure pipe 32 and a turbine 76 connected to the compressor 74, in turn in connection with an associated piping 78 for exhaust gases.

When stepping on the gas, the throttle valve 64 is opened again whereby the pressure in the inlet pipes 62 is raised, simultaneous as the partial flow of air with enhanced pressure that is led into the chamber 42 in the release valve presses the valve body 34 back against the valve seat 46. When the valve body seals against the valve seat again, the apertures are closed in the walls of the valve housing. The higher the pressure is, the harder the valve body will press against the valve seat.

The spring pressure of the spring 58 that operates on the valve body 34 may also be balanced such that the valve only opens partially at a small overpressure in the pipe.